As a type of an interdental brush, there is known one which includes bristles, a wire twisted with the bristles, and a handle attached to the wire, wherein a detachment preventing curved portion is formed at the base part of the wire, and the attachment of the wire to the handle is carried out by insert resin molding thereof (see, e.g., Patent Document 1).
Insert resin molding is high in equipment cost due to the structure of a molding die which is complicated and expensive. In addition, the operation of setting a wire to the die needs time and labor, and is therefore troublesome. Accordingly, an internal brush produced by insert resin molding is expensive. In view of this, the present applicant has developed an interdental brush and a method of producing the same which allow the interdental brush to be produced by simple resin molding without using insert resin molding (see Patent Document 2).